Tube and center heat exchangers such as used in motor vehicle air conditioning system condensers commonly have a plurality of parallel flat sided extruded tubes connected at opposite ends to a pair of headers and air centers between the tubes to facilitate efficient heat transfer to the surrounding area. The headers generally comprise a header plate with tube receiving apertures and a tank secured to the plate to supply refrigerant and receive same from the tubes. The air centers are brazed to the sides of adjacent tubes and the tubes are brazed or otherwise bonded to the header plates along with the tanks to assure leak free joints.
To enhance the ease of manufacture and reduce the cost while maintaining or improving durability and reliability, it has been proposed to form the headers as a laminated construction, as disclosed in U.S. patent application Ser. No. 07/200,321 filed May 31, 1988, now U.S. Pat. No. 4,903,389 and assigned to the assignee of this invention. In that arrangement, the headers simply comprise a flat inner tube plate that is apertured for receiving the ends of the tubes and serves as one side of the passage means. A flat outer tank plate is then aligned with and spaced from the inner plate and serves as a second side of the passage means. And a flat spacer plate conforming to and bonded between the margins of the inner tube plate and the outer tank plate acts to form the remaining boundaries of the passage means with the thickness of the spacer defining the spacing of the inner and outer plates to provide flow passages connecting the tube ends. This arrangement provides for improved burst pressure and low tooling costs and, in addition, enables a design flexibility which is important to allow selection of the number of passes, etc., with a minimal change in the structure in the manufacturing process.